This lesson is an introduction to melt and pour soap. It provides basic concepts that form the foundation of melt and pour soapmaking.

Why Choose Melt and Pour Soap Making?

Melt and pour soapmaking is a wonderful soapmaking process for those that don’t want to handle the toxic ingredient, sodium hydroxide (lye). Pre-made MP soap bases are formulated with sodium hydroxide, however, this ingredient is chemically altered during the formulation process, so there is no contact with the dangerous chemical in a finished tray of melt and pour soap base. ( Cold process soapmaking is the process in which you create soap from scratch and use the toxic ingredient, sodium hydroxide. )

MP Soap is great for children to work with and provides for endless creativity as you can experiment with color, form, fragrance and additives. MP Soap Base comes in several varieties of bases lending to many different visual elements ranging from opaque to clear. Clear soap is unique to MP Soap Base as cold process soap is always opaque.

Melt and Pour Soap: What is it?

Melt and Pour (MP) Soap Base is a man-made, commercially produced, water-soluble compound formulated for the purpose of cleansing the body. It comes in varying shades, depending on the formula and additives used. You can typically find white bases, clear bases, green tinted bases and yellow tinted bases.

Natural vegetable oils are saponified and used as a base for the MP Soap. Unlike traditional soap making, the saponification process is complete and no curing time is necessary. Working with MP Soap Base is great for those that don’t want to handle sodium hydroxide (lye).

When the soap is commercially produced, additives are incorporated into the formula to improve the base’s clarity, lather and craftability. MP Soap Base is a unique soap because it is specifically formulated to be heated, melted and solidified without changing the original qualities of the base.

While there can be creativity in the ingredients used to make MP Soap Base, those that work best are either water-based or made to be incorporated into water-based products. Learn more about ingredients, Click Here.

Natural vegetable oils have different fatty acid chain lengths and each different chain length contributes to different characteristics of the soap. Shorter fatty acid chain lengths are more water-soluble and produce large bubbles, quick lather, and a softer bar of soap. Longer fatty acid chain lengths are less water-soluble and produce smaller tight bubbles and a harder bar of soap. Different manufacturers use different fatty acids in their individual MP Soap Base formulas. The following are the most common fatty acids used, including chain length:

PH is a measure of the acidity or alkalinity of a solution. Since MP Soap Base formulas can vary from manufacturer to manufacturer, so can the pH. The typical pH range of MP Soap Bases is 8 to 9. You need this higher pH to attract dirt, cleanse the skin, and rinse away the soap. Soap with a low pH can be soft and leave bathtub rings. Soap with a high pH can cause skin irritation. If you are ever curious about the exact pH of your soap, you can test the pH of your soap with strips and solutions found at many local pool stores.

Best Used and Expiration Dates

MP Soap does not have an expiration date because it will not go rancid. The high percentage of propylene glycol required to produce this type of base acts as a natural preservative. Most MP Soap Bases have a “Best Used” date. The Best Used date is important because MP Soap Base can lose water and dehydrate over time.

If you find yourself with dehydrated MP Soap Base you can try adding in liquid glycerin (at 5-10%) to make it usable.

Melt Point

Different manufacturers have different formulas and thus different melt points to their MP Soap Base formulas. The typical melt point for most MP Soap Bases on the market is 115º-125ºF.

To raise the melt point of your soap, you can add 3% palm stearic acid to the soap base. Making this addition will likely cloud your base and decrease your lather, but is helpful when a higher melt point base is required. To add stearic acid, melt the stearic acid until liquid, which is approximately 160ºF. Melt the soap base to 150ºF. Blend the two together.

If is very important to know the melt point of your MP Soap Base.

Heating the base more than 30ºF above melt point may cause the soap to dehydrate and become prone to bloom.

Heating the base more than 50ºF above melt point may cause the soap to become brittle, reduce lather, and turn yellow.

Prolonged overheating of soap base will turn the base amber and produce a foul odor that may be difficult to mask with fragrance or essential oils.

Selling soap at a hot outdoor show or displaying soap in a warm store window could result in the soap softening or melting.

When mixing or combining different bases the overall melt point will change to the average of the bases mixed.

Pour Temperature

The majority of bases on the market have a recommended pouring temperature of 140º-145ºF. This temperature may be only several degrees lower than maximum temperatures that promote dehydration. Thus it is necessary to closely control the pouring temperature.

When pouring soap over embeds or when pouring soap in layers, it is important to adjust the pour temperature of the second pour of soap. If you do not adjust your pour temperature, the second pour of soap will melt the first pour of soap. To adjust the pour temperature, simply allow the soap to cool before you pour it. While cooling, if the soap forms a skin or thick layer of soap, simply mix it and it will melt with the soap below it. To prevent the first pour of soap from melting, the second pour of soap should be 125º-130ºF.

Melting Your MP Soap Base - Small Batches

A double boiler is the preferred method for heating and melting small batches of MP Soap Base. A double boiler prevents overheating, hot spots and water evaporation of the soap. Although heating MP Soap Base with a microwave can be popular, there are four reasons to avoid this.

There is little control for even heating creating hot spots.

It is likely the outer soap will boil before the inner soap has melted.

Water loss will cause disruption of the base formula and could result in MP Soap bloom and sweating.

Prolonged overheating can cause an amber discoloration. Although this discoloration does not affect the safety of the soap, it is not aesthetically pleasing. Once clear soap turns amber, it is not possible to return it to a clear color. You can add titanium dioxide to the soap to produce an opaque ivory soap that is safe for use.

Melting Your MP Soap Base - Big Batches

The preferred method for melting large batches of MP Soap Base is a water jacket melter with a digital thermostat. A water jacket is important because direct exposure to heating elements can cause the soap to turn amber. When using a water jacket melter, the thermostat should not be set higher than 130ºF. Soap should not be allowed to remain in the melter for more than 12 hours because prolonged overheating at high temperatures will cause the soap to turn amber.

Considerations for Re-Melting MP Soap Base

You can reheat MP Soap up to two times. If soap is reheated, add 1/2 tablespoon of distilled water per pound of MP Soap Base each time the soap is reheated. Soap should not be reheated more than twice because incorporating additional water may lead to clouding of clear base, difficulties unmolding, and MP Soap bloom.

Storing Your MP Soap Base

MP Soap Base should be stored in a cool and dry area away from direct sunlight and moisture. MP Soap Base can be stored in the original packaging or if opened, plastic airtight storage containers can be used (such as plastic shoe boxes). You can also seal your soap base in plastic storage bags. Always keep your base sealed up and airtight.